Anti-Arrhythmic Drugs - Howlett 4

Question 1

Arrhythmia

Answer 1

Disruption in the rate, rhythm, origin or conduction of the heartbeat
Causes include myocardial infarction, drug toxicity, electrolyte imbalance
Reduces ability of heart to pump blood
Can originate in any part of the heart

Question 2

Supraventricular arrhythmias

Answer 2

Arise in atria or AV node

Question 3

Ventricular arrhythmias

Answer 3

Arise in ventricles and are lethal

Question 4

Bradycardias

Answer 4

Slow heart rate
Too few beats per minute
Lower CO

Question 5

Tachycardias

Answer 5

Fast year rate
Too many beats per minute
Lower CO because ventricles cannot fill

Question 6

Non-pharmacological means to treat arrhythmias

Answer 6

1. Remove abnormal tissue
2. Pacemaker
3. Implantable cardioverter-defibrillator

Question 7

Treatment of tachycardias

Answer 7

Atrial or ventricular can be treated with anti arrhythmic drugs
1 + 3 are pro arrhythmic
Increase APD and increase refractory period

Question 8

Class 1

Answer 8

Na channel blocker
Lidocaine
Preferentially bind to and block Na channels in cardiac tissue that is damaged
Prevent reentry

Question 9

Class 2

Answer 9

Beta-blocker
Metoprolol
Block beta receptors in SNS in heart to decrease Ca overload
(Pain and stress causes SNS to increase Ca influx into heart, which can promote Ca overload which triggers DADs and EADs)
Slow HR, slow conduction velocity through the AV node and increase AV node refractory period

Question 10

Class 3

Answer 10

Increase APD
Amiodarone
Prolong ADP and prolong refractory period mainly by blocking K channels responsible for depolarizing the heart
Even in normal tissue

Question 11

Class 4

Answer 11

Ca channel blocker
Diltiazem, verapamil
Decrease Ca overload
Slow conduction velocity through AV node and increase AV node refractory period

Question 12

Other

Answer 12

Digoxin, adenosine

Question 13

Enhanced automaticity

Answer 13

Can occur in cells that show spontaneous depolarization (SA and AV nodes)
Increased SNS activity
Increased slope of spontaneous depolarization
Increased firing rate in AV node
Can also occur in muscle cells that do not show spontaneous depolarization
Can cause ectopic pacemaker: tachycardias when it is faster than SA node

Question 14

Triggered automaticity

Answer 14

Abnormal AP following normal AP when heart is overloaded with Ca
EADs
or DADs

Question 15

Reentry

Answer 15

AP activates heart more than once
Normal heart tissue with obstacle to conduction
Ischemic area, damage
AP cannot go through damaged area and goes wrong way, which can cause it to roll through again

Question 16

Digoxin

Answer 16

Mimics effects of PNS in heart, especially at the AV node
Acts like beta-blockers and Ca channel blockers
Slows AV conduction and decreases ventricular rate